Material and Energy Balance Widelia Ika Putri STP MSc wideliaikaputriubacid Basic Principles The mass and energy going into the box must balance with the mass and energy coming out ID: 662788
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Slide1
Unit Operation and Process Material and Energy Balance
Widelia Ika Putri, S.T.P., M.Sc.Slide2
wideliaikaputri@ub.ac.id
Basic PrinciplesThe mass and energy going into the box must balance with the mass and energy coming out.
The law of mass conservation states that mass can’t be created nor destroyed.The law of energy conservation states that energy can’t be created nor destroyed.Slide3
Mass Conservation
Milk X kgSo:Milk mass = skim milk mass + cream milk massX kg/minute = A kg/minute + B kg/minute
wideliaikaputri@ub.ac.id
Centrifugal separator
Skim milk
A kg
Cream milk
B kgSlide4
Energy Conservation
Food (chemical energy)So:Chemical energy entering body = mechanical energy leaving body
wideliaikaputri@ub.ac.id
Body
Mechanical
energySlide5
Energy Conservation
So:The heat lost by the heating water = the heat gained by the milk + the heat lost from heat exchanger to its surroundings
wideliaikaputri@ub.ac.id
Heat exchanger
Heating water
Heating milk
cool water
heat lost
MilkSlide6
Soal
Berapa air yang harus diuapkan dari pemekatan lar
. Garam 5% menjadi lar. Garam 20%?Berapa penurunan berat yang terjadi
jika
bahan
dikeringkan
dari
kadar
air 80%
menjadi kadar air 50%?
wideliaikaputri@ub.ac.idSlide7
Soal
Tentukan jumlah daging sapi tidak
berlemak (lean beef), daging babi berlemak (fat pork), dan air yang harus ditambahkan untuk membuat
adonan
sosis
sebanyak
100 kg.
dengan
syarat
:Lean beef => lemak 14%, protein 19%, air 67%
Fat pork => lemak 89%, protein 3%, air 8%Sosis =>
lemak 20%, protein 15%, air 65%wideliaikaputri@ub.ac.idSlide8
Soal
2. Pada pembuatan jam
buah-buahan digunakan perbandingan 45 buah : 55 gula.
Untuk
mendapatkan
konsistensi
jam yang
baik
, jam
harus
mengandung
padatan
terlarut 65%. Pada
proses pembuatan jam terdiri atas pencampuran buah dan gula
dengan
perbandingan
tersebut
,
penambahan
pektin
,
pemekatan
campuran
dalam
evaporator
vacum
sehingga
kandungan padatan
terlarut minimal 65%. Jumlah pektin yang diperlukan dipengaruhi
oleh
jumlah
gula
yang
ditambahkan
(
untuk
100 kg gula diperlukan pektin 1kg). Apabila buah yang digunakan mengandung padatan terlarut 10%. Hitung berat buah , gula dan pektin yang diperlukan? Untuk membuat jam 100 kg, dianggap bahwa padatan terlarut yang dimaksud berasal dari buah dan gula (pektin tidak dianggap).
wideliaikaputri@ub.ac.idSlide9
wideliaikaputri@ub.ac.id
Direct energy
Fuel and electricity used on the farm, in transport, in factories, in storage, selling, etc.
Energy consumed
Indirect energy
Energy which is used to build the machine, to make the packaging, to produce the electricity, etc. Slide10
wideliaikaputri@ub.ac.id
Energy unit
Btu
joule
kilocaloriesSlide11
wideliaikaputri@ub.ac.id
Heat
1
Latent Heat
Is the heat required
to
change the physical state of material, at constant temperature.
2
Sensible Heat
The heat which when added or subtracted from food materials changes their temperature and thus can be sensed .Slide12
Latent Heats (phase changes)
Vapourisation (L to V)Melting (S to L)Sublimation (S to V)www.themegallery.com
Company LogoSlide13
Sensible heat‘Sensible’ heat – heat/enthalpy that must be transferred to raise or lower the temperature of a substance or mixture of substances.
Heat capacities/specific heats (solids, liquids, gases,vapours)Use of mean heat capacities/specific heats over a temperature rangeUse of simple empirical equations to describe the variation of Cp with T
www.themegallery.comCompany LogoSlide14
Uses
Heat required for a processRate of heat removal from a processHeat transfer/design of heat exchangersProcess design to determine energy requirements of a processPump power requirements (mechanical energy balance)
Pattern of energy usage in operationProcess controlProcess design & developmentwww.themegallery.comCompany LogoSlide15
Soal
Pengering casein mengkonsumsi gas alam 4m3/h dengan
nilai kalori 800kJ/mol. Jika input pengering adalah 60 kg casein basah per jam, pengeringan dari kadar air 55% menjadi
kadar
air 10%,
hitung
keseluruhan
efisiensi
panas
pengering (hanya menggunakan
panas latent)?wideliaikaputri@ub.ac.idSlide16
Soal
2. Autoclave berisi 100 kaleng sop. Dipanaskan mencapai
suhu 100oC. Kaleng didinginkan mencapai 40oC sebelum meninggalkan autoclave. Berapa
air
dingin
yang
dibutuhkan
jika
air
masuk
pada
suhu 15o
C dan keluar suhu 35
oC? ket: Panas
spesifik sop 4,1 kJkg-1oC-1 & kaleng 0,5 kJkg-1oC-1 . Berat setiap kaleng 60 g & berisi sop 0,45 kg. diasumsikan panas di
dinding
autoclave1,6
x 10
4
kJ
dan
tidak
ada
panas
yang
hilang
melalui
dinding
.
wideliaikaputri@ub.ac.idSlide17
Soal
Sebuah pabrik minuman,
menghasilkan produk dengan kadar alkohol 16%
dan
kadar
gula
3%.
Untuk
membuatnya
diperlukan
campuran:Anggur 1 =>
kadar alkohol 14,6% & kadar gula 0,2%Anggur 2 => kadar alkohol 16,7% & kadar
gula
1,0%
Anggur
3 =>
kadar
alkohol
17,0% &
kadar
gula
12,0%
bila
diinginkan
membuat
100 kg
produk
,
berapa
berat masing2 minuman yang diperlukan?wideliaikaputri@ub.ac.idSlide18
Arigatou
Gozaimas